Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

1,261.

If 0.20 mol dm^-3 NaOH_(aq) was evaporated to yield 5.0g of solid NaOH, calculate the volume of NaOH _(aq) used. (Na = 23.0,O = 16:0; H = 1.00)

600cm-³

625cm³

1000³

1600 cm ³

View answer & explanation

Correct answer is B

Mole = 5/40 = 0.125 mole
:. 0.2 mole NaOH dissolved in 1000 cm³
0.125 mole NaOH dissolved in xcm³
xcm³ = \(\frac{0.215 x 1000}{0.2}\)
= 625cm³

1,262.

The oxidation number of sulphur in Fe₂(SO₄)₃ is

+2.

+4.

+6.

View answer & explanation

Correct answer is D

Fe₂(SO₄)₃ = 0
(+3 x 2) 9 3x + (-2 x 4 x 3) = 0
+6 + 3x -24 = 0
+3x - 18 = 0
3 x = 18
x = 18/3 = +6

1,263.

A gaseous mixture contains 0,256 g of hydrogen and 2.00 g of oxygen. The mole ration of hydrogen to oxygen in the mixture is (H=1.00; O=16,0)

1:1

2:1

1:4

8:1

View answer & explanation

Correct answer is B

Mole = \(\frac{Mass}{Molar Mas}\) : \(\frac{Mass}{Molar Mass}\)
\(\frac{0.256}{2}\) : \(\frac{2}{32}
0. 128 : 0.0625
\(\frac{0.128}{0.0625}\) : \(\frac{0.0625}{0.0625}\)
2 : 1

1,264.

An aqueous solution of Na₂CO₃ is

acidic

alkaline

amphoteric

neutral

View answer & explanation

Correct answer is B

No explanation has been provided for this answer.

1,265.

How many lone pair (s) of electrons is present in HF?